Behave fella im trying to help!
You say you have installed postgresql yourself multiple times!!! Could be your problem if you have installed it as its own instance and you havent issued a password and user.
Kali comes with postgresql in metaploit bundled.
BTW Metasploit and postgres work fine without the need to install separate instance of posgreqsl.
HOW ABT POST SOME COMMAND OUTPUT!!!
KindRegards
Dee